High Efficacy Semiconductor Light Emitting Devices Employing Remote Phosphor Configurations

ABSTRACT

A semiconductor light emitting apparatus a semiconductor light emitting device configured to emit light inside a hollow shell including wavelength conversion material dispersed therein or thereon. A semiconductor light emitting apparatus according to some embodiments is capable of generating in excess of 250 lumens per watt, and in some cases up to 270 lumens per watt.

RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 13/278,238, filed on Oct. 21, 2011 (Atty Docket5308-1340), which is a continuation-in-part of U.S. patent applicationSer. No. 13/087,510, filed on Apr. 15, 2011, 2011 (Atty Docket5308-1044IP), which itself is a continuation-in-part of U.S. patentapplication Ser. No. 12/273,216, filed on Nov. 18, 2008 (Atty Docket5308-1044), the disclosures of which are hereby incorporated byreference herein as if set forth in its entirety.

BACKGROUND

This invention relates to light emitting apparatus and methods ofassembling and operating same, and more particularly to semiconductorlight emitting apparatus and methods of assembling and operating same.

Semiconductor light emitting devices (“LEDs”), such as light emittingdiodes and laser diodes, are widely known solid-state lighting elementsthat are capable of generating light upon application of voltagethereto. Light emitting devices generally include a p-n junction, ananode ohmic contact for the p-type region of the device, and a cathodeohmic contact for the n-type region of the device. The device may beformed on a substrate, such as a sapphire, silicon, silicon carbide,gallium arsenide, gallium nitride, etc., substrate, or the device maynot include a substrate. The semiconductor p-n junction may befabricated, for example, from silicon carbide, gallium nitride, galliumphosphide, aluminum nitride and/or gallium arsenide-based materialsand/or from organic semiconductor-based materials.

Semiconductor LEDs may be used in lighting/illumination applications,for example, as a replacement for conventional incandescent and/orfluorescent lighting. As such, it is often desirable to provide alighting source that generates white light having a relatively highcolor rendering index (CRI), so that objects illuminated by the lightingmay appear as they do with incandescent light sources. The colorrendering index of a light source is an objective measure of the abilityof the light generated by the source to accurately illuminate a broadrange of colors. The color rendering index ranges from essentially zerofor poor white-light sources to nearly 100 for incandescent sources. ACRI greater than 80 is often desirable. A CRI greater than 90 isgenerally considered high quality and almost indistinguishable from anincandescent source.

In addition, the chromaticity of a particular light source may bereferred to as the “color point” of the source. For a white lightsource, the chromaticity may be referred to as the “white point” of thesource. The white point of a white light source may fall along a locusof chromaticity points corresponding to the color of light emitted by ablack-body radiator heated to a given temperature. Accordingly, a whitepoint may be identified by a correlated color temperature (CCT) of thelight source, which is the temperature of the heated black-body radiatorwith emission that matches the color or hue of the white light source.White light typically has a CCT of between about 2000K and 8000K. Whitelight with a CCT of 4000K is considered neutral white which generallydoesn't have an apparent hue. White light with a CCT of 8000K is morebluish in color, and may be referred to as “cool white”. “Warm white”may be used to describe white light with a CCT of between about 2600Kand 3500K, which is more reddish in color.

In order to produce white light, multiple LEDs emitting light ofdifferent colors of light may be used. The light emitted by the LEDs maybe combined to produce a desired intensity and/or color of white light.For example, when red-, green- and blue-emitting LEDs are energizedsimultaneously, the resulting combined light may appear white, or nearlywhite, depending on the relative intensities of the component red, greenand blue sources. However, in LED lamps including red, green, and blueLEDs, the spectral power distributions of the component LEDs may berelatively narrow (e.g., about 10-30 nm full width at half maximum(FWHM)). While it may be possible to achieve fairly high luminousefficacy and/or color rendering with such lamps, wavelength ranges mayexist in which it may be difficult to obtain high efficiency (e.g.,approximately 550 nm).

Alternatively, the light from a single-color LED may be converted towhite light by surrounding the LED with a wavelength conversionmaterial, such as phosphor particles. The term “wavelength conversionmaterial” is used herein to refer to any material that absorbs light atone wavelength and re-emits light at a different wavelength, regardlessof the delay between absorption and re-emission and regardless of thewavelengths involved. Accordingly, the term “wavelength conversionmaterial” may be used herein to refer to materials that are sometimescalled fluorescent and/or phosphorescent and often referred to as“phosphors”. In general, phosphors absorb light having shorterwavelengths and re-emit light having longer wavelengths. As such, someor all of the light emitted by the LED at a first wavelength may beabsorbed by the phosphor particles, which may responsively emit light ata second wavelength. For example, a blue emitting LED may be surroundedby a yellow phosphor, such as cerium-doped yttrium aluminum garnet(YAG). The resulting light, which is a combination of blue light andyellow light, may appear white to an observer.

Accordingly, efforts have been made to integrate a semiconductor lightemitting device with wavelength conversion material to provide asemiconductor light emitting apparatus. The wavelength conversionmaterial may be coated on the LED itself, may be provided in a drop ofmaterial between the semiconductor LED and the dome of an LED (alsoreferred to as a shell or lens) and/or may be provided remote from thesemiconductor LED by providing wavelength conversion material inside,outside and/or within the dome of an LED and/or on/within anothersurface remote from the LED.

SUMMARY

A semiconductor light emitting apparatus according to some embodimentsincludes a wavelength conversion element comprising wavelengthconversion material, and a plurality of light emitting diodes that areoriented to emit light to impinge upon the wavelength conversionelement. The semiconductor light emitting apparatus may produce greaterthan 250 lumens per watt at a color temperature of between 2000 K and8000 K.

The light emitting diodes may include blue light emitting diodes. Thelight emitting diodes may be connected in parallel. In particularembodiments, the light emitting diodes may have an area greater thanabout 1 mm², and in some embodiments the light emitting diodes each havean area of about 3 mm². For example, the diodes may have dimensions ofabout 1.75 mm×1.75 mm or more, and in some cases up to 2.75 mm×2.75 mm.For example, in some embodiments, the light emitting diodes may eachhave an area of about 4 mm² with dimensions of about 2 mm×2 mm.

An apparatus according some embodiments may produce greater than 250lumens per watt at a color temperature of between 4000 K and 5000 K. Forexample, an apparatus according to some embodiments may produce greaterthan 250 lumens per watt at a color temperature of about 4400 K, and insome cases up to 270 μm/W.

An apparatus according some embodiments may produce greater than 250lumens per watt, and in some cases up to 270 μm/W at a total drivecurrent of 350 mA or less at room temperature.

An apparatus according to some embodiments includes a plurality of lightemitting diodes having cross sectional areas selected to provide acurrent density of less than 15 A/cm² at a drive current at which thesemiconductor light emitting apparatus produces greater than 250 lumensper watt at a color temperature of between 2000 K and 8000 K. In someembodiments, the light emitting diode has an area selected to provide acurrent density of less than 10 A/cm² at a drive current at which thesemiconductor light emitting apparatus produces greater than 250 lumensper watt at a color temperature of between 2000 K and 8000 K, and insome embodiments the light emitting diode has an area selected toprovide a current density of less than 5 A/cm² at a drive current atwhich the semiconductor light emitting apparatus produces greater than250 lumens per watt at a color temperature of between 2000 K and 8000 K.In some embodiments, the light emitting diode has an area selected toprovide a current density of less than 2.5 A/cm² at a drive current atwhich the semiconductor light emitting apparatus produces up to 270lumens per watt at a color temperature of between 2000 K and 8000 K.

The apparatus may further include a substrate on which the plurality oflight emitting diodes are disposed, a transparent outer shell coveringthe substrate and the light emitting devices and defining a volumebetween the light emitting diodes and the shell, and an optical materialremotely located at least a first distance away from the one or morelight emitting devices for affecting light emitted from the one or morelight emitting devices. The transparent outer shell may include quartzand may have a diameter greater than 36 mm. In some embodiments, thediameter of the transparent outer shell may be about 40 mm. In furtherembodiments, the diameter of the transparent outer shell may be about 45mm and in some cases 62 mm.

A light emitting apparatus according to some embodiments includes asubstrate, a plurality of light emitting diodes disposed on thesubstrate, a transparent outer shell covering the substrate and thelight emitting devices and defining a volume of space between the lightemitting diodes and the shell, and an optical material remotely locatedat least a first distance away from the one or more light emittingdevices for affecting light emitted from the one or more light emittingdevices. The semiconductor light emitting apparatus produces greaterthan 250 lumens per watt at a color temperature of between 2000 K and8000 K. In some embodiments, the semiconductor light emitting apparatusproduces up to 270 lumens per watt at a color temperature of between2000 K and 8000 K.

The optical material may include a phosphor material. The phosphormaterial may be disposed on the shell. In some embodiments, the phosphormaterial may be coated on an inner or outer surface of the shell.

The apparatus may include light emitting devices adapted for a lightemission having a color rendering index of about 80 or more. In someaspects, the apparatus may include light emitting devices adapted for alight emission having a color rendering index of about 90 or more.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A a perspective view of a semiconductor light emitting apparatusaccording to various embodiments,

FIG. 1B is a cross-sectional view of a semiconductor light emittingapparatus according to other embodiments.

FIGS. 2A and 2B are cross-sectional views of packaged semiconductorlight emitting devices.

FIGS. 3-10 are cross-sectional views of semiconductor light emittingapparatus according to various other embodiments.

FIGS. 11A-14 are cross-sectional views of elongated hollow wavelengthconversion tubes according to various embodiments.

FIGS. 15-18 are cross-sectional views of semiconductor light emittingapparatus according to still other embodiments.

FIG. 19 graphically illustrates efficiency in lumens per watt as afunction of CCT for semiconductor light emitting apparatus according tovarious embodiments.

FIGS. 20A, 20B and 20C are a top view, a cross-section and a bottomview, respectively, of an LED according to some embodiments.

FIGS. 21 and 22 illustrate various geometries of substrates of FIGS.20A-20C, according to various embodiments described herein.

FIG. 23 is a cross-sectional view of a semiconductor light emittingapparatus according to other embodiments.

FIG. 24 is a schematic circuit diagram illustrating parallel connectionof light emitting diodes in a semiconductor light emitting apparatusaccording to some embodiments.

DETAILED DESCRIPTION

The present invention now will be described more fully with reference tothe accompanying drawings, in which various embodiments are shown. Thisinvention may, however, be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the invention to thoseskilled in the art. In the drawings, the size and relative sizes oflayers and regions may be exaggerated for clarity. Like numbers refer tolike elements throughout.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentinvention. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprising”, “including”, “having” and variants thereof, when used inthis specification, specify the presence of stated features, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, steps, operations,elements, components, and/or groups thereof. In contrast, the term“consisting of” when used in this specification, specifies the statedfeatures, steps, operations, elements, and/or components, and precludesadditional features, steps, operations, elements and/or components.

It will be understood that when an element such as a layer, region orsubstrate is referred to as being “on” another element, it can bedirectly on the other element or intervening elements may also bepresent. Furthermore, relative terms such as “beneath” or “overlies” maybe used herein to describe a relationship of one layer or region toanother layer or region relative to a substrate or base layer asillustrated in the figures. It will be understood that these terms areintended to encompass different orientations of the device in additionto the orientation depicted in the figures. Finally, the term “directly”means that there are no intervening elements. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items and may be abbreviated as “/”.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the present invention.

Embodiments of the invention are described herein with reference tocross-sectional and/or other illustrations that are schematicillustrations of idealized embodiments of the invention. As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments of the invention should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing. For example, a region illustrated or described as arectangle will, typically, have rounded or curved features due to normalmanufacturing tolerances. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe precise shape of a region of a device and are not intended to limitthe scope of the invention, unless otherwise defined herein.

Unless otherwise defined herein, all terms (including technical andscientific terms) used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand this specification and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

FIGS. 1A and 1B are a perspective view and a cross-sectional view ofsemiconductor light emitting apparatus according to various embodimentsof the present invention. As shown in FIGS. 1A and 1B, thesesemiconductor light emitting apparatus include an elongated hollowwavelength conversion tube 110 that comprises an elongated wavelengthconversion tube wall 112 having wavelength conversion material 114uniformly or non-uniformly dispersed therein. As used herein, a tubedenotes a long hollow object that may be, but need not be, cylindrical.Accordingly, the tube may be circular, elliptical, ellipsoidal and/orpolygonal. A semiconductor light emitting device 120 is oriented to emitlight 122 inside the elongated hollow wavelength conversion tube 110 toimpinge upon the elongated wavelength conversion tube wall 112 and thewavelength conversion material 114 dispersed therein. In someembodiments, the semiconductor light emitting device 120 may be apackaged light emitting diode 130 that includes a mounting substrate 124and a dome 126 on the mounting substrate 124, wherein the semiconductorlight emitting device 120 is located between the mounting substrate 124and the dome 126. One or more electrical leads 128 may extend from themounting substrate 124. As also shown in FIGS. 1A and 1B, the tube wall112 defines a tube axis 132, and the semiconductor light emitting device120 is configured to emit light 122 generally symmetrically about anemission axis and is oriented such that the emission axis is generallycoincident with the tube axis 132.

Various configurations of the semiconductor light emitting device 120,the mounting substrate 124 and the dome 126 may be provided according tovarious embodiments of the present invention. In some embodiments, thepackaged semiconductor light emitting device 130 may be represented by acommercially available LED, such as a Cree® EZ1000™ LED, manufactured bythe assignee of the present invention, and described in the Data SheetCPR3CR, Rev. A, entitled Cree® EZ1000™ LEDs Data SheetCxxxEZ1000-Sxx000, copyright 2006, Cree, Inc., available on the Web atcree.com. As indicated in this data sheet, these LEDs may use a singlesemiconductor die of size 980/980 μm² or about 1 mm². These LEDs mayoperate at a voltage of about 3 V (more typically about 3.3 V), and acurrent of about 350 mA (current density of about 35 A/cm²) for an inputpower of about 1 watt. The Cree EZ1000 LED may be manufactured under oneor more of the following U.S. patents/applications, the disclosures ofwhich are hereby incorporated herein in their entirety as if set forthfully herein: U.S. Pat. No. D566,057, issued Apr. 8, 2008, entitled LEDChip; U.S. Application Publication No. 2008/0173884, published Jul. 24,2008, entitled Wafer Level Phosphor Coating Method and DevicesFabricated Utilizing Same; U.S. Application Publication No.2008/0179611, published Jul. 31, 2008, entitled Wafer Level PhosphorCoating Method and Devices Fabricated Utilizing Same; and U.S.application Ser. No. 29/284,431, filed Sep. 7, 2007, entitled LED Chip.However, other commercially available packaged LEDs or bare LED dice maybe used.

In some embodiments, the light emitting device 130 may be an LED chip asillustrated in U.S. application Ser. No. 13/018,013, filed Jan. 31, 201,entitled Horizontal Light Emitting Diodes Including Phosphor Particles,the disclosure of which is hereby incorporated herein in its entirety asif set forth fully herein.

The LED may be provided on a silver (Ag) header and encapsulated with adome comprising, for example, Hysol® OS4000 fast curing water-whiteepoxy casting compound, marketed by Loctite. For increased reflectivity(and thus brightness), the silver header can also be coated with amixture of silicone with a high percentage of titanium dioxide powder.However, in other embodiments, other materials, such as epoxy, siliconeand/or other transparent encapsulants may also be used. Moreover, theLED need not have a dome, so that a bare die or a domeless LED also maybe used. In some embodiments, as shown in FIG. 1A, the semiconductorlight emitting device 120 may be adjacent but not within the elongatedhollow wavelength conversion tube 110. In other embodiments, as shown inFIG. 1B, the semiconductor light emitting device 120 may be at leastpartially within the elongated hollow wavelength conversion tube 110. Instill other embodiments, the transparent dome 126 may be entirely withinthe elongated hollow wavelength conversion tube 110, whereas themounting substrate 124 may be entirely outside and up against an end ofthe elongated hollow wavelength conversion tube.

In fact, FIGS. 1A and 1B also illustrate methods of assembling asemiconductor light emitting apparatus according to some embodiments,wherein a dome 126 that surrounds a semiconductor light emitting device120 that is on a substrate 124 is inserted at least partially into anend of an elongated hollow wavelength conversion tube 110 havingwavelength conversion material 114 dispersed therein. The dome may bepress-fit inside the tube or an adhesive or other attaching element maybe used.

The elongated hollow wavelength conversion tube 110 may be constructedfrom a sheet of plastic, epoxy, silicone, glass, quartz, and/or othertransparent or translucent material, such as the aforementioned OS4000material, that contains phosphor dispersed therein. The material may bemixed with phosphor at a desired concentration and then formed into asheet, which is allowed to cure. The sheet may be rolled and glued intoa tube and cut to a desired length. Alternatively, straws of plasticmaterial including phosphor encapsulated therein may be provided and cutto size. Moreover, the hollow wavelength conversion tube 110 may bemolded, extruded and/or formed by other conventional processes. Thephosphor may be conventional YAG phosphor, conventional (Ca, Si, Ba)SiO₄:Eu²⁺ (BOSE) phosphor and/or other conventional phosphors that mayvary in composition and/or concentration depending upon thecharacteristics of the semiconductor light emitting device 120 and/orother parameters. The elongated hollow wavelength conversion tube 110may be evacuated, air-filled or filled with an inert and/or reactivegas. The tube may also include a solid and/or gel therein to provide,for example, encapsulant, index matching, etc. The wavelength conversionmaterial 114 may be uniformly or non-uniformly dispersed in theelongated wavelength conversion tube wall 112. Uniform or non-uniformcomposition and/or concentration may be employed.

Dimensionally, the elongated hollow wavelength conversion tube 110 mayhave a length of between about 1 mm and about 100 mm, and an innerdiameter of between about 0.5 mm and about 10 mm. The inner diameter canbe larger, e.g., 20-30 mm in some embodiments. The tube wall 112 mayhave a thickness of between about 0.05 mm and about 2 mm. Wavelengthconversion particles may be dispersed therein at concentrations betweenabout 1% and about 70% by weight. The use of an elongated hollowwavelength conversion tube according to various embodiments of theinvention may provide efficient white light. For example, a Cree EZ1000LED having about a 1 mm² size. In some embodiments, a Cree EZ2750 diehaving a 7.5 mm² die size may be used. The LED is driven with a drivecurrent of about 350 mA at room temperature in combination with anelongated hollow wavelength conversion tube that is about 45 mm long,having an inside diameter of about 9 mm and a wall thickness of about 2mm, and being fabricated from a sheet of flexible transparent siliconehaving BOSE phosphor dispersed therein at a concentration of about 30%by weight, can produce about 170 lumens of light output, about 160lumens/watt efficiency at a correlated color temperature of about 4700K,and about 150 lumens/watt efficiency at a correlated color temperatureof about 5500K. FIG. 19 graphically illustrates efficiency inlumens/watt (lm/w) vs. CCT, for these example embodiments. It will beunderstood that, in FIG. 19, various concentrations of phosphors may beused to obtain the desired color temperature.

Without wishing to be bound by any theory of operation, high efficiencywhite light production may be obtained according to various embodimentsof the present invention by causing almost all of the light that isemitted by the semiconductor light emitting device 120 to strike theelongated wavelength conversion tube wall 112 at an oblique angle. Morespecifically, referring to FIG. 2A, a packaged light emitting diode mayemit light in a Lambertian pattern 220, wherein the radiant intensity isdirectly proportional to the cosine of the angle between the observer'sline of sight and an axis 210 that is normal to the surface of thesemiconductor light emitting device 130. The Lambertian pattern 220 maybe obtained by designing the light emitting device 120 to emit light ina Lambertian pattern, and designing the dome 126 so as not to changethis emission pattern, or by designing the light emitting device 120 toemit light in a non-Lambertian pattern and by designing one or moreoptical elements in the dome 126, so that the light that emerges fromthe dome 126 is Lambertian. In other embodiments, as shown in FIG. 2B, apackaged or unpackaged light emitting diode may emit light in a focused(i.e., narrow far-field emission) pattern 230, wherein more radiantenergy is emitted closer to the axis 210 of emission than to the sides.Again, this focused pattern may be obtained by designing the lightemitting device 120 to emit light in a focused pattern and designing thedome 126 so as to not change this emission pattern or by designing thelight emitting device 120 to emit light in a non-focused pattern and bydesigning one or more optical elements in the dome 126 so that the lightemerges from the dome 126 in a focused pattern. Other conventionalemission patterns may be used.

Conventionally, the dome 126 may be designed to be hemispherical so thatthe emitted light 122 crosses the dome perpendicular to the domesurface. Some embodiments may employ a hemispherical dome sitting on ashort cylindrical base. Thus, if phosphor is coated on the inner and/orouter surfaces of the dome 126, much of the emitted light will bebackscattered into the device 120. In sharp contrast, when the packagedLED 130 is mounted relative to an elongated hollow wavelength conversiontube as shown in FIG. 1B, at least 20% of the emitted light 122 canstrike the elongated hollow wavelength conversion tube wall 112 at anoblique angle, as shown in FIG. 1B. The backscattering of light backinto the semiconductor light emitting device 120 may be substantiallyreduced. Moreover, in some embodiments, at least about 90% of theemitted light 122 can strike the elongated hollow wavelength conversiontube wall 112 at an oblique angle, as shown in FIG. 1B. Thebackscattering of light back into the semiconductor light emittingdevice may be substantially reduced.

Accordingly, some embodiments of the present invention may allow lightthat is emitted from the semiconductor light emitting device 120 to passthrough the dome 126 generally orthogonal thereto, but to strike theelongated hollow wavelength conversion tube wall 112 substantiallyoblique thereto. Thus, some embodiments of the invention may be regardedas providing a primary optical surface, such as the dome 126 of thepackaged light emitting diode 130, wherein Lambertian radiation causesalmost all of the emitted light to cross the surface orthogonal thereto,and the elongated wavelength conversion tube wall 112 provides asecondary optical surface including wavelength conversion material 114dispersed therein, wherein almost all of the light impinges on thesecondary optical surface 112 at an oblique angle thereto.

Without wishing to be bound by any theory of operation, high efficiencyof embodiments of the present invention may also be explained due todifferent path lengths that may be established within the elongatedhollow wavelength conversion tube 110. In particular, referring to FIGS.3 and 3A, the emitted light 122 from the semiconductor light emittingdevice 120 reflects off the inner surface of the tube wall 110, as shownby ray 310, and also refracts within the tube wall, as shown by ray 312.Additional internal reflection takes place from the outer wall, as shownas by ray 314, and some of the original light 316 emerges from the tube.The path through the wall 112 is indicated by ray 312. In contrast, whenlight strikes a phosphor particle 114 that is embedded within the tubewall 112, it is converted and scattered in all directions, as shown bythe rays 322.

Accordingly, as shown in FIGS. 3 and 3A, except for near thesemiconductor light emitting device 120, very little light is reflectedback at the semiconductor light emitting device 120. In order for thelight 122, such as blue light, that emerges from the semiconductor lightemitting device 120 to convert, for example to yellow light, it mustimpinge on a wavelength conversion material (e.g., phosphor) particle114. Once it does convert, it is desirable for the converted emission322 to escape with minimal obstruction, not only from the LED 130 butalso from other wavelength conversion material particles 114. Thus, itis desirable for the wavelength conversion material layer to appearthick for the blue light, but thin for the yellow emission 322. The tube110 helps to achieve this, because the blue light has a longer path 312through the tube wall 112 at grazing incidence and the same amount ofconversion can be achieved with less wavelength conversion material 114.Thus, since the blue light has a longer path length 312 through the tubewall 112 at grazing incidence, the tube appears thicker for the incomingblue light. Since the tube appears thicker, a lower concentration ofphosphor may be used. By using a lower concentration of phosphor, lessphosphor obstruction may be provided. Accordingly, in some embodiments,the elongated hollow wavelength conversion tube 110 is oriented relativeto the semiconductor light emitting device 120, so as to provide alonger path length 312 through the elongated wavelength conversion tubewall 112 for light 122 that is emitted by the semiconductor lightemitting device 120 that does not strike the wavelength conversionmaterial 114 embedded therein, without increasing the path length oflight 322 that is converted by the wavelength conversion material 114embedded therein.

Various configurations of elongated hollow wavelength conversion tubesmay be provided according to various embodiments of the presentinvention. For example, as shown in FIG. 4, the elongated hollowwavelength conversion tube 110 includes first and second opposing ends110 a, 110 b, and the semiconductor light emitting device 120 isadjacent the first end 110 a. It will also be understood that in FIG. 4and other figures to follow, the semiconductor light emitting device 120is shown outside the elongated hollow wavelength conversion tube 110. Inthese embodiments, a reflector, lens and/or other optical element may beprovided to direct the light 122 inside the tube 110. However, in otherembodiments, the semiconductor light emitting device 120 may extend atleast partially into the elongated hollow wavelength conversion tube110. In yet other embodiments, the semiconductor light emitting device120 extends fully into the elongated hollow wavelength conversion tube110.

In FIG. 4, the second end 110 b is an open end. In contrast, in FIG. 5,the second end 110 b is a closed second end, which may be provided by acap 510. The cap 510 may be reflective and/or may contain wavelengthconversion material therein. The cap 510 may be planar or non-planar asillustrated. For example, a hemispherical, prismatic, textured and/ormicrolens-covered cap may be provided. The wavelength conversionmaterial in the cap 510 may be same as, or different from the wavelengthconversion material 114 in the elongated wavelength conversion tube wall112 in terms of composition and/or concentration. In other embodiments,as shown in FIG. 6, the second end 110 b is a crimped second end 610. Itwill be understood that the word “crimped” is used herein to denote atapered end, and not to denote any particular manufacturing method.Thus, FIG. 6 illustrates embodiments of bullet-shaped elongated hollowwavelength tubes 110.

Embodiments of the invention that have been described above employ oneor more semiconductor light emitting devices 120 at a first end 110 a ofthe elongated hollow wavelength conversion tube 110. However, in otherembodiments, at least one semiconductor light emitting device may beprovided at both ends of the tube 110. For example, as shown in FIG. 7,a first semiconductor light emitting device 120 a is included adjacentthe first end 110 a of the elongated hollow wavelength conversion tube110, and oriented to emit light inside the elongated hollow wavelengthconversion tube 110. A second semiconductor light emitting device 120 bis located adjacent the second end 110 b and is oriented to emit light122 b inside the elongated hollow wavelength conversion tube.

FIG. 8 illustrates other embodiments wherein a double-sided reflector810 is included in the elongated hollow wavelength conversion tube 110between the first and second semiconductor light emitting devices 120 a,120 b. The double-sided reflector 810 may be embodied as a mirror, areflective sphere and/or other device that reflects at least some lightimpinging thereon. For example, a spherical, prismatic, textured and/ormicrolens-covered double-sided reflector may be provided. Thedouble-sided reflector 810 may be flat or non-planar as shown. Thedouble-sided reflector also may include wavelength conversion material.FIG. 9A illustrates other embodiments wherein the elongated hollowwavelength conversion tube 110 is crimped as shown at 910, between thefirst and second semiconductor light emitting devices 120 a, 120 b. FIG.9A shows a gradual crimp that is fully closed, whereas FIG. 9Billustrates an abrupt crimp 920 that is not fully closed.

FIG. 10 illustrates other embodiments wherein the first and secondsemiconductor light emitting devices 120 a, 120 b are oriented inback-to-back relation within the elongated hollow wavelength conversiontube 110, such that the first semiconductor device 120 a emits light 122a towards the first end 110 a and the second semiconductor lightemitting device 120 b emits light 122 b towards the second end 110 b. Inother embodiments, the first and/or second ends 110 a, 110 b may includea cap, such as a cap 510 of FIG. 5, may be crimped or tapered, such asby including crimp 610 of FIG. 6, or may be open as shown. Also, the twoends need not have the same type of termination.

The elongated hollow wavelength conversion tube 110 itself may also havemany different configurations. For example, in FIG. 11A, the elongatedtube wall 112 includes inner and outer surfaces wherein the inner and/orouter surfaces are textured as shown. The texturing may be uniformand/or non-uniform. Texturing may enhance scattering of light. Moreover,FIG. 11B illustrates other embodiments wherein a sawtooth pattern orother pattern may be used to guide the unconverted light, so as tofurther increase its path length in the wavelength conversion tube.Other light guiding patterns may also be used.

In other embodiments, as shown in FIGS. 12 and 13, a supporting layermay be provided to support the elongated wavelength conversion tube wall112. In FIG. 12, the supporting layer 1210 is on the outer surface ofthe elongated hollow wavelength conversion tube wall 112, whereas inFIG. 13, the supporting layer is on the inner surface of the elongatedhollow wavelength conversion tube wall 112. In fact, embodiments ofFIGS. 12 and 13 may be fabricated by coating a wavelength conversionmaterial 114 inside or outside a supporting tube 1210, 1310,respectively, so that the elongated hollow wavelength conversion tube110 may actually be embodied as a coating on a supporting material. Instill other embodiments, a supporting layer may be provided on both theinside and outside surfaces of the elongated wavelength conversion tubewall 112.

Multiple concentric elongated hollow conversion tubes 112 also may beprovided according to other embodiments. In particular, as shown in FIG.14, a first elongated hollow wavelength conversion tube 112 a and asecond elongated hollow wavelength conversion tube 112 b are providedcoaxial to one another. The tubes may be spaced apart and may besupported by a common supporting layer 1410. In fact, embodiments ofFIG. 14 may be fabricated by coating inner and outer surfaces of asupporting layer 1410 with wavelength conversion material 114. Inembodiments of FIG. 14, the wavelength conversion material 114 dispersedin the first and second elongated wavelength conversion tube walls 112a, 112 b may be the same or may be different in composition and/orconcentration.

FIG. 15 illustrates other embodiments wherein a plurality of elongatedhollow wavelength conversion tubes 110 are provided for a semiconductorlight emitting device 120 or a cluster of semiconductor light emittingdevices 120. Thus, a semiconductor light emitting device 120, or acluster of semiconductor light emitting devices 120, is adjacent a firstend of each of the tubes. In FIG. 16, the elongated hollow wavelengthconversion tubes 110 extend about a common origin, and the semiconductorlight emitting device 120 is adjacent the common origin. In someembodiments, FIG. 16 may be regarded as a cross-sectional view showing aplurality of hollow wavelength conversion tubes 110 that surround acommon origin and extend within the plane of the figure to provide atwo-dimensional array. FIG. 16 may also be regarded as illustrating across-section of a three-dimensional array of hollow elongated tubes 110that extend around a common axis 1600, as shown by arrow 1610. Thus,flower petal-like designs may be provided for semiconductor lightemitting apparatus according to these embodiments.

Various embodiments of the invention as described above may also beregarded as providing a semiconductor light emitting filament that maybe analogized to the filament of a conventional incandescent lamp or toa miniature fluorescent bulb. Thus, as shown in FIG. 17, an elongatedhollow wavelength conversion tube 110 includes a packaged semiconductorlight emitting device 130 at either end. The packaged semiconductordevices 130 may be mounted on a base 1710 using heat conductivestandoffs 1720 and/or other conventional mounting techniques. A bulb1730 and a screw-type base 1740 may be provided, so that the combinationof the elongated hollow wavelength conversion tube 110 and the packagedsemiconductor light emitting devices 130 at opposite ends thereofprovides a filament for a drop-in replacement for an incandescent bulb.It will be understood that FIG. 17 provides a simplified representationand that a drop-in replacement for an incandescent bulb may also employvoltage conversion circuits, thermal management systems, etc.

In other embodiments, as shown in FIG. 18, the filaments are orientedend-to-end in a linear array. Heat sinks 1810 and/or a reflector 1820may also be provided.

Some embodiments are capable of generating white light at an efficacy ofup to 270 lumens/watt, an efficacy that may enable the broader adoptionof solid state lighting devices in applications that have traditionallybeen served by incandescent and/or fluorescent light sources.

Increased efficacy of light emission according to some embodiments maybe obtained by increasing the size of the light emitting diode chip inthe apparatus. A larger chip can produce more optical output power andmay be driven at a lower forward voltage, both of which can increase theefficiency of the apparatus. In addition, using a high operating currentof, for example, 350 mA may be closer to peak efficiency for a largerchip. Furthermore, high conversion efficiency can be obtained usingwavelength conversion techniques described herein.

In particular, efficacy of 208 lumens per watt was obtained using an LEDchip having dimensions of 1.75 mm×1.75 mm, for a total chip area ofabout 3 mm², driven at a drive current of 350 mA at room temperature.Light generated by the apparatus had a color temperature of 4579 K. Evengreater lumens per watt can be achieved using a larger LED chip. Forexample, in excess of 230 lumens per watt can be achieved using a lightemitting diode may have an area of about 4 mm² with dimensions of about2 mm×2 mm. In some embodiments, two LEDs having chip dimensions of 2.75mm×2.75 mm each may be operated in parallel to obtain up to 270 lm/W.

Accordingly, a semiconductor light emitting apparatus according to someembodiments includes a wavelength conversion element comprisingwavelength conversion material, and a light emitting diode that isoriented to emit light to impinge upon the wavelength conversionelement. The semiconductor light emitting apparatus may produce greaterthan 200 lumens per watt at a color temperature of between 2000 K and8000 K.

The light emitting diode may include a blue light emitting diode. Inparticular embodiments, the light emitting diode may have an areagreater than about 1 mm², and in some embodiments the light emittingdiode has an area of about 3 mm² and in some cases up to 7.5 mm². Forexample, the diode may have dimensions of about 1.75 mm×1.75 mm, and insome cases up to 2.75 mm×2.75 mm. At a drive current of 350 mA, thiscorresponds to a current density of about 11.4 A/cm² for the 1.75 mmchip.

An apparatus according some embodiments may produce greater than 200lumens per watt at a color temperature of between 4000 K and 5000 K. Forexample, an apparatus according to some embodiments may produce greaterthan 200 lumens per watt at a color temperature of about 4600 K.

An apparatus according some embodiments may produce greater than 200lumens per watt at a drive current of 350 mA at room temperature.

An apparatus according to some embodiments includes a light emittingdiode having a cross sectional area selected to provide a currentdensity of less than 30 A/cm² at a drive current at which thesemiconductor light emitting apparatus produces greater than 200 lumensper watt at a color temperature of between 2000 K and 8000 K. In someembodiments, the light emitting diode has a cross sectional areaselected to provide a current density of less than 20 A/cm² at a drivecurrent at which the semiconductor light emitting apparatus producesgreater than 200 lumens per watt at a color temperature of between 2000K and 8000 K, and in some embodiments the light emitting diode has across sectional area selected to provide a current density of less than15 A/cm² at a drive current at which the semiconductor light emittingapparatus produces greater than 200 lumens per watt at a colortemperature of between 2000 K and 8000 K. In some cases, the lightemitting diode has a cross sectional area selected to provide a currentdensity of less than 2.5 A/cm² at a drive current at which thesemiconductor light emitting apparatus produces up to 270 lumens perwatt at a color temperature of between 2000 K and 8000 K.

FIGS. 20A, 20B and 20C are a top view, a cross-section and a bottomview, respectively, of a semiconductor LED device 300 that may be usedin some embodiments.

In embodiments of FIG. 20A, the outer face 320 b′ of the substrate 320of the LED 300 includes at least one groove, such as an X-shaped groove315 therein. Multiple X-shaped grooves and/or other shaped grooves mayalso be provided. Moreover, as shown in FIG. 20C, in some embodiments,the anode contact 360 and the cathode contact 370 may collectivelyoccupy at least about 90% of the active diode region area.

Specifically, FIGS. 20A-20C illustrate an embodiment wherein the innerface 320 c of the substrate 320 is a square inner face 320 c havingsides that are about 1,000 μm long, the outer face 320 b′ is a squareouter face having sides that are about 642 μm long, and a thickness ordistance t between the square inner and outer faces (also referred to as“height”) is about 335 μm, so as to define an area ratio between theouter face 320 b and the inner face 320 c of about 0.41. The dioderegion 310 may also be a square, having sides that are about 1,000 μmlong. A small gap 320 of about 75 μm is provided. A calculation of theactive attach area may be made as follows:

Total active area of diode region=751,275 μm²(cathode)+70,875μm²(gap)+70,875 μm²(anode)=893,025 μm².

Total active attach area=751,275 μm²(cathode)+70,875 μm²(anode)=822,150μm². Thus, the active attach area is at least about 90% of the activediode region area.

Table 1 illustrates various configuration geometries of the substrate320 that may be provided according to various other embodiments. It willbe understood that the “area ratios” used herein are based on thedimensions of the sides of the faces and do not include any addedsurface area due to texturing, grooves and/or other light extractionfeatures.

TABLE 1 Base Top (Inner) Area, (Outer) Area, Area Ratio Aspect RatioDesignator μm² μm² (Top/Base) (Height/Base) DA1000 1000000 412164 0.4120.335 DA850 722500 242064 0.335 0.394 DA700 490000 116964 0.238 0.5

FIG. 21 illustrates these embodiments. Specifically, the top row ofTable 1 illustrates various embodiments wherein the inner face 320 c isa square inner face having sides that are about 1000 μm long (total area1,000,000 μm²), the outer face 320 b is a square outer face having sidesthat are about 642 μm long (total area 412,164 μm²) and a distance(height) between the square inner and outer faces is about 335 μm so asto define an area ratio of the outer face to the inner face (top tobase) of about 0.41, and an aspect ratio of height to a side of theinner face (base) of about 0.335. These embodiments are also illustratedin FIG. 20B. The second row of Table 1 illustrates embodiments whereinthe inner face 320 c is a square inner face having sides that are about850 μm long (total area 722500 μm²), the outer face 320 b is a squareouter face having sides that are about 492 μm long (total area 242064μm²) and a distance (height) between the square inner and outer faces isabout 335 μm so as to define an area ratio of the outer face to theinner face of about 0.33 and an aspect ratio of height to base of about0.39. Finally, the third row of Table 1 illustrates various embodimentswherein the inner face 320 c is a square inner face having sides thatare about 700 μm long (total area about 722500 μm²), the outer face 320b is a square outer face having sides that are about 342 μm long (totalarea about 116964 μm²) and a distance height between the square innerand outer faces is about 335 μm so as to define an area ratio of theouter face to the inner face of about 0.24 and an aspect ratio of heightto base of about 0.5.

FIG. 22 and Table 2 illustrate other embodiments wherein the inner face320 c is a rectangular inner face of size 350 μm×470 μm. In the firstline of Table 2, the height is about 175 μm thick, and the outer face320 b is a rectangle of size 177 μm×297 μm, so as to provide a base(inner) area of 164500 μm² and a top (outer) area of 52569 μm. The arearatio of top to base is about 0.32, and the ratio of height to base isabout 0.5. The second line of Table 2 illustrates a thicker height ofabout 290 μm, so that the top has sides of about 44 μm×164 μm, leadingto an area ratio of about 0.044 and a ratio of height to base of about0.8.

TABLE 2 Base Top (Inner) (Outer) Area, Area Ratio Aspect RatioDesignator Area, μm² μm² (Top/Base) (Height/Base) DA350 - 164500 525690.319568389 0.5 Standard 175 μm thick DA350 164500 7216 0.0438662610.828 Extreme - 290 μm thick

Accordingly, embodiments of Table 1 and Table 2, corresponding to FIGS.21 and 22, can provide light emitting diodes wherein an area ratio ofthe outer face to the inner face is less than or about 0.4 and, in someof these embodiments, the aspect ratio of the height to a side of theinner face is at least about 0.3. These tables and figures alsoillustrate other embodiments wherein the area ratio of the outer face tothe inner face is less than or about 0.33 and, in some embodiments, theaspect ratio of the height to a side of the inner face is at least about0.4. These tables and figures also illustrate yet other embodimentswherein the area ratio of the outer face to the inner face is less thanor about 0.04 and, in some embodiments, the height to base aspect ratiois at least about 0.8.

It has been found that light extraction may be improved as the ratio ofthe outer area to the inner area is reduced. The larger area devices,such as the DA1000 described on the first line of Table 1 can provideadditional extraction by providing a groove, as was illustrated in FIG.20A. This would appear to indicate that further extraction benefit wouldbe obtained by a further reduction in the ratio of the top to base, butthis may be expensive due to the blade width that may be needed forbeveling the sidewalls. On the smaller devices, such as the DA350described in the first row of Table 2, there may be no further gain atblue light in further increasing the ratio, so that an aspect ratio ofabout 0.32 may already be sufficient for maximum blue light extraction.

Embodiments of the invention that are capable of greater than 200 lumensper watt at a color temperature of between 2000 K and 8000 K are shownin FIG. 23, which illustrates a cross-sectional view of a light emittingapparatus 410 that is capable of greater than 230 lumens per watt, andin some cases up to 250 lumens per watt, and in some cases, more than250 lumens per watt. In the light emitting apparatus 410, packaged LEDs416 are disposed on a platform 434 of a body 412. In the embodimentsshown in FIG. 23, the LED chips 418 are provided in LED packages 416;however, unpackaged LEDs 418 could also be used. In some embodiments,the packaged LEDs 416 include blue light emitting XLamp® LEDsmanufactured by Cree, Inc., Durham, N.C., the assignee of the presentinvention. The LEDs may include large area power LEDs having an areagreater than 1 mm², and in some cases having an area of about 4 mm² andin some cases up to 7.5 mm². In some embodiments, a single blue XLamp®LED manufactured by Cree, Inc., may be used. The power LEDs 418 used insome embodiments may be capable of being driven at very high forwardcurrent levels. For example, power LEDs 418 used in some embodiments maybe capable of being driven at up to 3000 mA. Large LED die, e.g. LED diehaving dimensions of 2.75 mm×2.75 mm may be driven at up to 5000 mA.

LEDs 418 and/or LED packages 416 can be mounted directly over theplatform 434 of the body 412, or as illustrated, the LED packages 416can be mounted over mounting substrate 436. the LEDs can be mounted inother locations/directions than the bottom base and facing up—forinstance, on pillars or posts, facing sideways, etc. The LEDs 418 can beattached within the LED packages 416 using any suitable die attachmaterials and/or methods. For example, in one aspect the LEDs 418 can beattached within packages 416 using metal-to-metal bonding techniquesincluding flux-assisted eutectic die attach, metal-assisted non-eutecticdie attach, or thermal compression die. Metal-to metal die attachincludes a robust die attach resulting in a more reliable die attachduring operation of remote component 410. This can result in fewer LEDsbecoming detached during operation. In the alternative, the LEDs 418 canbe attached using silicone, silver (Ag) epoxy, solder. Any suitable dieattach can be used.

As FIG. 23 illustrates, an outer shell 414 is provided over the platform434. The cover 414 is formed of a transparent material such as glass orplastic, and defines a volume over the LEDs 416. The volume may befilled with air, or some other transparent substance or gas. The shell414 may have a dome shape, a hemispherical shape or other similar shapeincluding elongated shapes. The shell 414 includes an outer surface 451and an inner surface 452. Outer and inner surfaces 451 and 452 can becoated with one or more layers of optical materials to thereby emitlight external from the shell 414 having desired optical properties. Forillustration purposes, both the outer and inner surfaces 451 and 452 ofthe apparatus 410 shown in FIG. 23 are coated with optical material.However, in some aspects only one of the outer or inner surface 451 and452 may be coated. In particular embodiments, a mixture of YAG phosphorand transparent silicone encapsulant may be applied to the shell 414. AnEu-doped barium orthosilicate (BOSE) phosphor may also be used alone orin combination with a YAG phosphor. An oxynitride material, such asalpha/beta-SiAlON may also be used.

In some embodiments, a red phosphor may be incorporated into thewavelength conversion material. Suitable red phosphors are disclosed,for example, in U.S. application Ser. No. 13/15315, filed Jun. 3, 2011,entitled Methods Of Determining And Making Red Nitride Compositions,U.S. application Ser. No. 13/152,863, filed Jun. 3, 2011, entitled RedNitride Phosphors, and/or U.S. application Ser. No. 13/154,872, filedJun. 7, 2011, entitled Gallium-Substituted Yttrium Aluminum GarnetPhosphor And Light Emitting Devices Including The Same, the disclosuresof which are hereby incorporated herein in its entirety as if set forthfully herein. In other embodiments, a red emitter may be incorporatedinto the LED package as described in U.S. Publication No. 2011/-227469,published Sep. 22, 2011, entitled Led Lamp With Remote Phosphor AndDiffuser Configuration Utilizing Red Emitters, the disclosure of whichis hereby incorporated herein in its entirety as if set forth fullyherein.

When electrical current is passed through LED packages 416, LEDs 418 canemit light 480 towards an inner surface 452 of the shell 414. Opticalmaterials coated on either the inner and/or outer surfaces 451 and 452can interact with light emitted from the one or more LEDs 418 to emitlight 485 having a desired wavelength and/or brightness.

Optical materials can include luminescent materials having an amount ofwavelength conversion material 450. Any suitable phosphor can be usedwith remote component 410. Wavelength conversion material 450 cangenerate light of desired perceived colors when the light emitted fromthe LEDs 418 interacts with the phosphor. Other materials, such asdispersers and/or index matching materials may be included in thewavelength conversion material 450. Wavelength conversion material 450can be applied and/or coated to shell 414 using any suitable method. Inone aspect, a predetermined weight of wavelength conversion material 450can be mixed with an adhesive material and loaded in a syringe. Themixture can then be coated to outer surface 451 and/or inner surface 452of shell 414 and can optionally be cured. In one aspect, the mixture maybe spray coated, however, any suitable coating method 410 can be used.For example, wavelength conversion material 450 can coat the insideand/or outside of the shell 414 by spraying, brushing, molding,encapsulating, adhering, dipping, and/or any combinations thereof. Anysuitable coating method can be used. The shell 414 can be cleaned,measured, and inspected prior to assembly over body 412 such thatdefects in the coating can be detected and cured prior to assembly.Adhesive material can include any suitable material, not limited tosilicone or other encapsulants.

Still referring to FIG. 23, the wavelength conversion material 450 isremotely located with respect to the LEDs 418 and LED packages 416.Wavelength conversion material 450 therefore can be excluded from beingdisposed, for example, directly on and over LEDs 416 or within LEDpackages 418. Stated differently, the LED packages 416 can be free ofany wavelength conversion material. The wavelength conversion material450 can be located any suitable distance from the LEDs, for example, atleast approximately 1 mm or greater. As FIG. 23 illustrates, LEDs 418can be mounted a first distance D over upper surface 432 of body 412.This can, in part, allow light to be reflected and emitted below theLEDs 418. First distance D can include any suitable distance. Phosphorcan be remotely located from the one or more LEDs 418 and/or LEDpackages 416 a minimum distance of D2 from wavelength conversionmaterial 450. The minimum distance D2 can include any suitable distance,for example, at least approximately 1 mm or greater. In one aspect, theminimum distance D2 can be equal to approximately 20 mm or greater,depending on the desired size of remote component. Any suitable minimumdistance D2 is contemplated herein. LEDs 418 and/or LED packages 416 canalso be located a maximum distance D3 from phosphor 20 material 450. Inone aspect, LEDs and/or LED packages 416 can be disposed substantiallybeneath or below shell 414. FIG. 20 illustrates LEDs 418 disposedsubstantially beneath a substantially circular, domed, and/or roundedshell 414. However, shell 414 can include any suitable size and/orshape. In addition, LEDs 418 and/or LED packages 416 can be disposed atany position below shell 414. As illustrated, LEDs 418 and LED packages416 can be substantially disposed beneath a center of shell 414, thecenter corresponding to maximum distance D3. However, LEDs 418 and/orLED packages 416 can be positioned at suitable location below shell 414,for example, to the left or right of center. Size, number, andpositioning of LEDs 418 and LED packages 416 can affect light emission.Any suitable size and number of LEDs 418 and/or LED packages 416 can beused, and the LEDs 418 and/or LED packages 416 can be disposed at anysuitable location substantially below shell 414.

Still referring to FIG. 23, the shell 414 can further include a neckportion N for engaging inner wall 430 of the body 412. Neck N is adaptedto engage inner wall 430 using an adhesive or any suitable material.Neck N could also be adapted to frictionally or threadingly engage theinner wall 430 of the body 412. Any suitable method can be used tosecure the neck N of the shell 414 to the inner wall 430 of the body. Inone aspect, the neck N can be disposed below the plane on which the LEDs418 are mounted, and can include any suitable size to accommodatesufficient structural strength when connecting and/or engaging to thebody 412. In one aspect, the neck can include an outer diameter L1 ofapproximately 40 mm or less. In one aspect, the neck N can include anouter diameter L1 of approximately 30 mm or less, for example,approximately 25.7 mm or less. However, the neck N can include anysuitable outer diameter L1. FIG. 20 further illustrates the neck Nincluding an inner diameter, L2. The inner diameter L2 can correspond tothe thickness of the shell 414, for example, where the cover includes athickness of approximately 1 mm or less, the neck N can include an innerdiameter of approximately 39 mm or more. The shell 414 can include anysuitable thickness and any suitable inner diameter L2. In one aspect,the neck N can include an inner diameter L2 of approximately 30 mm orless, for example, approximately 24.5 mm or less. However, the neck Ncan include any suitable inner diameter L2.

The shell 414 and the neck N can also have any suitable height. In oneaspect, the cover can include a height H measured from the base of theneck N to the furthest point of the outer surface. For example, forspherical shapes, the height can be measured from the topmost curvatureof the shell 414. In one aspect, the shell 414 can have a height H ofapproximately 50 mm or less. In one aspect, the shell 414 can have aheight approximately 40 mm or less. In one aspect, the shell 414 caninclude a height of approximately 35 mm or less, for example,approximately 33.4 mm or less. However, any suitable height H of coveris hereby contemplated. Similarly, the neck N can have a height H2. Inone aspect, the neck N height H2 can include approximately 5 mm or less.In one aspect, the height H2 can be approximately 3 mm or less. In oneaspect, the height H2 is approximately 2.8 mm. The neck N can includeany suitable size, shape, height, and/or diameter. The shell 414 can beapproximately 40 mm or less. In one aspect, the shell 414 can have aninner diameter of approximately 35 mm or less, for example,approximately 34.8 mm. The shell 414 can have an outer diameter fromwhich light can be emitted. In one aspect, the shell 414 can have anouter diameter of approximately 45 mm or less. In one aspect, an outerdiameter of the shell 414 can be approximately 36 mm or less. Anysuitable size, shape, height, and/or diameter of the shell 414 is herebycontemplated.

An apparatus 410 described herein can target various colors andwavelengths of light. Light emitted from the apparatus 410 can include acombination of the light from the LEDs 418 and/or LED packages 416 incombination with the light emitted from wavelength conversion material450. In one aspect, the apparatus 410 disclosed herein can consume areduced amount of power as compared to conventional bulbs which requireat least approximately 40-120 W. For example, remote components 410described herein can use approximately 12.5 W or less of power, and insome cases less than one watt of power. In one aspect, remote components410 described herein can use approximately 10 W or less of power. Thus,remote component devices and systems described herein can use severaltimes less energy than conventional lighting products and light bulbs,thereby saving energy and reducing energy-related costs. In one aspect,remote components 410 described herein target cool white, outdoor white,neutral white, and warm white colors.

Apparatus 410 as described herein can, for example and withoutlimitation, offer light output of approximately 800 lumens (lm) or moreat 500 mA (12.5 W) at cool white, outdoor white, neutral white, and warmwhite color points. In some aspects, apparatus 410 as described hereincan, for example and without limitation, offer light output ofapproximately 800 lumens (lm) or more at 10 W or less at cool white,outdoor white, neutral white, and warm white color points.

Apparatus 410 disclosed herein can be used alone and/or in lightingfixtures offering a minimum CRI of 75 for cool white, which correspondsto a range of 5,000 K to 10,000 K CCT. Apparatus 410 disclosed hereincan also offer, for example, a minimum CRI of 80 for warm white, whichcorresponds to a range of 2,600K to 3,700K CCT. Apparatus 410 disclosedherein can also offer, for example, a minimum CRI for color points of 90CRI which corresponds to a range of 2,600K to 3,200K CCT. Remotecomponent 410 devices can be used for both standard and high voltageconfigurations. In one aspect, brightness can be improved by usingoptimized methods and/or procedures described herein. For example, anapproximately 6% or more improvement in brightness can be attained usingmetal-to-metal die 15 attach as previously described herein. Anapproximately 4% or more improvement in brightness for example can beattained using a white solder mask around the one or more LEDs or LEDpackages.

In one aspect, typical performance at 12.5 W can include at leastapproximately 1040 lm and at least approximately 83 lm/W. Typicalperformance at 12.5 W can also include at least as minimum of 80 CRI and3000 CCT within a 30F bin. Uniformity of light emitted from remotecomponent 410 can be controlled by controlling the uniformity of thewavelength conversion material 450. In one aspect, uniformity can becontrolled by adjusting a spray pattern of the wavelength conversionmaterial 450 for instances where wavelength conversion material is spraycoated to the outer surface 451 or inner surface 452 of shell 414.

In other aspects, an apparatus 410 as described herein is capable ofgenerating more than 200 μm/W at a color temperature of between 2000 Kand 8000 K. In some cases, an apparatus 410 as described herein iscapable of generating more than 230 μm/W, and in still other cases anapparatus 410 as described herein is capable of generating over 230μm/W, and in some cases over 250 μm/W, and in some cases up to 270 μm/W.Higher lm/W output may be obtained by driving the apparatus at lowercurrent mA. For example, a lm/W output of 250 μm/W was obtained bydriving an apparatus including a single 4 mm² LED device at 80 mA, whichcorresponds to about 0.22 W of power consumption at 2 A/cm², while 230μm/W has been obtained by driving the device at 350 mA, corresponding toabout 1 W of power at 8.75 A/cm².

An apparatus according some embodiments may produce greater than 230lumens per watt at a color temperature of between 4000 K and 5000 K. Forexample, an apparatus according to some embodiments may produce greaterthan 230 lumens per watt at a color temperature of about 4600 K.

An apparatus according some embodiments may produce greater than 230lumens per watt at a drive current of 350 mA or less at roomtemperature.

An apparatus according to some embodiments includes a light emittingdiode having a device area selected to provide a current density of lessthan 15 A/cm² at a drive current at which the semiconductor lightemitting apparatus produces greater than 200 lumens per watt at a colortemperature of between 2000 K and 8000 K. In some embodiments, the lightemitting diode has a device area selected to provide a current densityof less than 10 A/cm² at a drive current at which the semiconductorlight emitting apparatus produces greater than 200 lumens per watt at acolor temperature of between 2000 K and 8000 K, and in some embodimentsthe light emitting diode has a cross sectional area selected to providea current density of less than 5 A/cm² at a drive current at which thesemiconductor light emitting apparatus produces greater than 200 lumensper watt at a color temperature of between 2000 K and 8000 K. In someembodiments the light emitting diode has a cross sectional area selectedto provide a current density of less than 2.5 A/cm² at a drive currentat which the semiconductor light emitting apparatus produces greaterthan 250 lumens per watt, and in some cases up to 270 lm/W, at a colortemperature of between 2000 K and 8000 K.

Devices according to further embodiments may produce in excess of 250lumens per watt. In particular, it has been found that it is possible toincrease the efficiency of a light emitting apparatus by providingmultiple large area light emitting diodes in parallel with each lightemitting diode running at a lower peak current of about 85 mA. Forexample, a device according to some embodiments includes four (4) 4 mm²LED devices, such as Cree EZ2000 devices, operating in parallel at aforward current of about 85 mA, for a total current supplied to thepackage of about 350 mA and a total power consumption of 0.95 W.Parallel connection of the LEDs 418 in the light emitting apparatus 410is illustrated in FIG. 24. Operating multiple lamps in parallel has beenfound to increase the efficiency in lm/W by about 7%.

Furthermore, it has been found that increasing the size of the shell 414can increase the efficiency of the device. In some embodiments, theshell 414 may have a diameter of about 36 mm. However, it has been foundthat increasing the shell diameter to 40 mm, and in some cases to 45 mmcan increase the efficiency of the apparatus. Furthermore, it has beenfound that using a quartz globe instead of, for example, a borosilicateglass globe, can increase the efficiency of the apparatus. The quartzglobe may be approx 1.5 mm thick, although the thickness may not beconstant across the globe. The relevant parameter is opticaltransmission. Quartz globes have better transmission (% T˜99.5%)compared, for example, to borosilicate glass globes (˜98.5%)

It has further been determined that the method of coating the wavelengthconversion material on the inside of the shell 414 can increase theefficiency of the apparatus. For example, using a fill-and-dump methodto coat the inside of the shell 414 with a wavelength conversionmaterial has been found to increase the efficiency of the devicecompared, for example, to spray coating the wavelength conversionmaterial. In a fill and dump method, the shell 414 is filled with aliquid containing wavelength conversion particles in suspension, and theexcess liquid is subsequently dumped out, allowing a coating of liquidincluding the wavelength conversion particles to remain on the innersurface of the shell 414. The base material for the phosphor particlesmay be silicone, which may be the same material that is used to spraythe globes on the outside (when that method is used). This is the sametype of material regularly used to encapsulate other LED packages. Thethickness for the inside coating may be similar to the sprayed/outsidecoatings. Depending on the targeted color point, the thickness of thewavelength conversion material may generally be between about 0.15 and0.35 mm.

An apparatus 410 including four 4 mm² LED devices connected in paralleland including a 40 mm diameter quartz shell 414 on which a wavelengthconversion layer 450 was formed by a fill-and-dump method was found toexhibit a 254 lumens/watt with a total luminous flux of 242 μm when runat a total forward current of 350 mA. Another device exhibited 270 μm/Wwith a total flux of 260 μm when run at 350 mA. The light output by theapparatus was found to have a CCT of 4408.

Many different embodiments have been disclosed herein, in connectionwith the above description and the drawings. It will be understood thatit would be unduly repetitious and obfuscating to literally describe andillustrate every combination and subcombination of these embodiments.Accordingly, the present specification, including the drawings, shall beconstrued to constitute a complete written description of allcombinations and subcombinations of the embodiments described herein,and of the manner and process of making and using them, and shallsupport claims to any such combination or subcombination. For example,any of the embodiments illustrated herein may include a baresemiconductor light emitting device die or a packaged semiconductor LED;an open-ended, capped or crimped end; one or more bare or packagedsemiconductor light emitting devices that are entirely outside,partially inside or fully inside the elongated hollow wavelengthconversion tube; one or more supporting layers; one or more elongatedhollow wavelength conversion tubes arranged concentrically or in a two-or three-dimensional array and/or packaged to include heat sinks,reflectors, driving circuitry and/or other components.

In the drawings and specification, there have been disclosed embodimentsof the invention and, although specific terms are employed, they areused in a generic and descriptive sense only and not for purposes oflimitation, the scope of the invention being set forth in the followingclaims.

What is claimed is:
 1. A semiconductor light emitting apparatuscomprising: a wavelength conversion element comprising wavelengthconversion material; and a plurality of light emitting diodes that areoriented to emit light to impinge upon the wavelength conversionelement; wherein the semiconductor light emitting apparatus producesgreater than 250 lumens per watt at a color temperature of between 2000K and 8000 K.
 2. An apparatus according to claim 1 wherein the lightemitting diodes are connected in parallel.
 3. An apparatus according toclaim 1 wherein each of the light emitting diodes has an area greaterthan about 1 mm².
 4. An apparatus according to claim 1 wherein at leastone of the light emitting diodes has an area of about 4 mm².
 5. Anapparatus according to claim 1 wherein at least one of the lightemitting diodes has an area greater than 7 mm².
 6. An apparatusaccording to claim 1 wherein the semiconductor light emitting apparatusproduces between 250 lumens per watt and 270 lumens per watt.
 7. Anapparatus according to claim 1 wherein the semiconductor light emittingapparatus produces up to 270 lumens per watt.
 8. An apparatus accordingto claim 1 wherein the semiconductor light emitting apparatus producesgreater than 250 lumens per watt at a color temperature of between 4000K and 5000 K.
 9. An apparatus according to claim 1 wherein thesemiconductor light emitting apparatus produces greater than 250 lumensper watt at a color temperature of about 4400 K.
 10. An apparatusaccording to claim 1 wherein the semiconductor light emitting apparatusproduces greater than 250 lumens per watt at a total drive current of350 mA or less at room temperature.
 11. An apparatus according to claim1, wherein each of the light emitting diodes has a cross sectional areaselected to provide a current density of less than 15 A/cm² at a drivecurrent at which the semiconductor light emitting apparatus producesgreater than 250 lumens per watt at a color temperature of between 2000K and 8000 K.
 12. An apparatus according to claim 1, wherein each of thelight emitting diodes has a cross sectional area selected to provide acurrent density of less than 10 A/cm² at a drive current at which thesemiconductor light emitting apparatus produces greater than 250 lumensper watt at a color temperature of between 2000 K and 8000 K.
 13. Anapparatus according to claim 1, wherein each of the light emittingdiodes has a cross sectional area selected to provide a current densityof less than 5 A/cm² at a drive current at which the semiconductor lightemitting apparatus produces greater than 250 lumens per watt at a colortemperature of between 2000 K and 8000 K.
 14. An apparatus according toclaim 1, wherein each of the light emitting diodes has a cross sectionalarea selected to provide a current density of less than 2.5 A/cm² at adrive current at which the semiconductor light emitting apparatusproduces greater than 250 lumens per watt at a color temperature ofbetween 2000 K and 8000 K.
 15. An apparatus according to claim 1,wherein each of the light emitting diodes has a cross sectional areaselected to provide a current density of less than 9 A/cm² at a drivecurrent of about 85 mA at a color temperature of between 2000 K and 8000K.
 16. The apparatus of claim 1, further comprising: a substrate,wherein the plurality of light emitting diodes are disposed on thesubstrate; a transparent outer shell covering the substrate and thelight emitting devices and defining a volume of space between the lightemitting diodes and the shell; and an optical material remotely locatedat least a first distance away from the one or more light emittingdevices for affecting light emitted from the one or more light emittingdevices.
 17. The apparatus of claim 16, wherein the transparent outershell comprises quartz.
 18. The apparatus of claim 17, wherein theoptical material is disposed on an inner surface of the transparentouter shell, wherein the optical material is between the plurality oflight emitting diodes and the transparent outer shell.
 19. The apparatusof claim 17, wherein the transparent outer shell has a diameter greaterthan or equal to 36 mm.
 20. The apparatus of claim 17, wherein thetransparent outer shell has a diameter of greater than or equal to 40mm.
 21. The light emitting apparatus of claim 1, wherein light emittedby the light emitting apparatus has a color rendering index of about 80or more.
 22. The light emitting apparatus of claim 1, wherein lightemitted by the light emitting apparatus has a color rendering index ofabout 90 or more.
 23. The light emitting apparatus of claim 1, whereinthe wavelength conversion material is spaced apart from the plurality oflight emitting diodes.
 24. The light emitting apparatus of claim 23,wherein the wavelength conversion material is spaced apart from theplurality of light emitting diodes by at least a distance of 1 mm.
 25. Alight emitting apparatus, comprising: a substrate; a plurality of lightemitting diodes disposed on the substrate and connected in parallel; atransparent outer shell covering the substrate and the light emittingdevices and defining a volume of space between the light emitting diodesand the shell; and an optical material remotely located at least a firstdistance away from the one or more light emitting devices for affectinglight emitted from the one or more light emitting devices; wherein thesemiconductor light emitting apparatus produces greater than 250 lumensper watt at a color temperature of between 2000 K and 8000 K.
 26. Thelight emitting apparatus of claim 25, wherein the optical materialcomprises a phosphor material.
 27. The light emitting apparatus of claim26, wherein the phosphor material is disposed on the transparent outershell.
 28. The light emitting apparatus of claim 26, wherein thephosphor material is coated on an inner or outer surface of thetransparent outer shell.
 29. The light emitting apparatus of claim 25,wherein light emitted by the light emitting apparatus has a colorrendering index of about 80 or more.
 30. The light emitting apparatus ofclaim 25, wherein light emitted by the light emitting apparatus has acolor rendering index of about 90 or more.
 31. The light emittingapparatus of claim 25, wherein the transparent outer shell has adiameter greater than or equal to 36 mm.
 32. The light emittingapparatus of claim 25, wherein the transparent outer shell has adiameter greater than or equal to 40 mm.
 33. The light emittingapparatus of claim 25, wherein the transparent outer shell comprisesquartz.